Diesel automatic oil cooler

AnderN · 14th October 2020, 10:12

Greetings,

I have a 2004 ZT (facelift) saloon diesel with JATCO automatic gearbox. At some point the car couldn't reach and keep the engine operating temperature so I changed the thermostat but unfortunately no change in behavior. Even after a long run the engine was still able to make only around 65°C (instead of ~90°C). I started to suspect the automatic transmission oil cooler that also includes one thermostat inside but I can't find it anywhere to buy (either the thermostat or the whole cooler). Other cars with the same engine/gearbox combination (such as LR Freelander) seem to use a different cooler for the gearbox oil.

As a workaround, I have added one more thermostat to the cooling circuit, this improved the operating temperature to ~80-85°C. It is definitely better than before and far better than experiencing some overheating problems but it's still not perfect.

Question -- do you know where to buy the transmission oil cooler for my car? It appears to no longer available at rimmers or anywhere else:
https://rimmerbros.com/Item--i-GRID001593

Or is there anyone in here who had the same problem? How did you solve it?

Thanks in advance!

Sonic ZS · 14th October 2020, 20:50

Hi Ondrej, I'm not familiar with the oil thermostat, but if the cooler isn't available, I'd check ebay or your local breakers for a good, used unit

clf · 14th October 2020, 21:40

This is a common problem, but whilst I have not heard of an oil thermostat, almost certainly the replacement thermostat you have fitted is faulty. If it is an inline thermostat you fitted, it is either faulty, fitted incorrectly, or is letting too much coolant past before it opens.

The full definitive background is HERE (a very long read)

How to fit the thermostat is HERE from THIS post.

My personal preference is a Wahler 3029.89. If you could get a 3029.92 it would be better, but these are difficult to find, and expensive. But others are acceptable.

An alternative option is the Meziere inline housing.

Load on the engine and distance is important, speeds of between 40-70mph for 10 miles should see it reach temperature of 82-88 degrees.

There is a lot of information about this issue and modification. Search inline thermostat and you will see. If you decide to read it all, the winter will be over, and you will not notice lol.

If you really want to replace the oil cooler, Mickyboy has one listed HERE. But I would still confirm the inline thermostats first.

SD1too · 15th October 2020, 07:50

Quote:

Originally Posted by AnderN

... the automatic transmission oil cooler that also includes one thermostat inside ...

Greetings Ondrej,

Are you sure that you're not thinking of the engine oil cooler which (according to RAVE) does have an integral thermostatic valve as part of the filter housing?

Or perhaps one of these fitted to very early diesel automatics (probably not yours) and with its own thermostatically controlled fan?

Simon

Arctic · 15th October 2020, 09:13

this maybe what you are after double check before purchase.

http://mgrovergenuine.co.uk/genuine-...-transmission/

ceedy · 15th October 2020, 09:27

Can't see why anything outside of the motor and Cooling circuit should have any effect on the engine temperature in a negative temps way

? .

Any effect/load would only ever be temps upwards if at all ?

C.

AnderN · 22nd October 2020, 23:10

Thank you very much for your fast answers, gentlemen! I'll try to shed more light in some parts of the story ...

I have this car for 10+ years now and made over 100k miles on it. Currently it has around 200k miles on the clock (~300k km). It is an excellent car and I love it, for a long time it was the only facelifted ZT here in the Czech Republic (now there are 2-3 more as the prices fell down rapidly a couple years ago). Anyway, to your points:

@Sonic ZS: no chance to get a used oil cooler anywhere around

@clf: thanks for the links, it is a long reading and with the three small kids home it took me a while to read through it :-) anyway, the car is typically used for longer distances (60-120 miles but even longer) at speeds around 70-90 mph on highways ... there are only two situations when the engine can fully reach the operating temperature -- either speeds above 100 mph or a long standstill traffic during tropical days in summer. In such case the temperature can go over 100°C and I can hear the fan running (I think it starts at 106°C according to both the RAVE and my own experience) ... although I haven't tried to boil it on a home cooker I'm quite sure the new thermostat works properly ;-) the extra inline thermostat that I installed helped to improve the temperature, it is just not 100%

@SD1too: no, I need the later 'fluid' cooler, #1 at this page: https://rimmerbros.com/Item--i-GRID001593

@Arctic: thanks but that's just one of the hoses, I need the cooler, see the link above

@ceedy: with the latest 'fluid' cooler (see the link above) the engine coolant goes through the transmission oil cooler (the oil is cooled by the same water as the engine) ... the oil cooler is supposed to have an extra thermostat built in but if this thermostat is broken and remains open permanently, the engine starts being cooled more than needed, therefore cannot reach the operating temperature unless it is under very high load (100+ mph on a highway or something like that).

I was trying to find out if the same transmission oil cooler was used in some other cars including BMWs, too. Unfortunately, I didn't find any. Even in R75/ZT there were three different transmission oil coolers -- one for petrol engines, and two for diesel (the original air cooler and the later fluid cooler that I have in my car). Obviously, the BMWs with M47R engine used different automatic transmissions and different coolers at their time.

clf · 23rd October 2020, 01:25

Quote:

Originally Posted by AnderN

@clf: the extra inline thermostat that I installed helped to improve the temperature, it is just not 100%

.......... because of this, I would bet that your new proper thermostat is opening early, and that the inline thermostat is letting too much coolant past, (when fully closed). I have experienced this with an inline thermostat (x3).

The proper thermostats are known to open early, so much so, a special 'version 3' type was commissioned a number of years ago, but these too, are not perfect apparently.

I cannot understand how the transmission oil cooler could cool the coolant so much that it effects the rest of the engine. Both coolant thermostats, if working, would not fully open until they reached at least 88 degrees for the 'proper' thermostat. The coolant comes cooled from the radiator to the oil cooler, then to the engine, gets hot, the thermostat opens, at the prescribed temperature (88 degrees), and then back to the radiator to the cooler.

I would still suggest trying a different inline thermostat, testing it for water tightness before fitting. A £10 thermostat and 30 minutes to fit, is so much cheaper and easier than an oil cooler that receives cooled coolant. Reject if water leaks from the bowl quickly, whilst cold. Heat in a pan of hot water to make sure it opens at least once before testing. Also when fitting, do not push by the bulb, I suspect I damaged my first one by doing this.

Mike Noc · 23rd October 2020, 09:04

Yes the ATF won't have an adverse effect on the engine cooling.

SD1too · 23rd October 2020, 10:12

Quote:

Originally Posted by AnderN

... I can hear the fan running (I think it starts at 106°C according to both the RAVE and my own experience) ...

Hi Ondrej,

It starts at 100°C (some interpretations of RAVE are mistaken).

Quote:

Originally Posted by AnderN

... the oil cooler is supposed to have an extra thermostat built in ..

From where did you get this information Ondrej? I can't find any reference to it in RAVE. As I asked earlier, are you thinking of the engine oil cooler? What do other diesel owners say?

I don't think that your problems have anything to do with the transmission fluid cooler. Your evidence points to the dual thermostat installation. When you did this work, did you refill and bleed the cooling system according to MGR's procedure?

Simon

14th October 2020, 20:50	#2
Sonic ZS Posted a thing or two 75 Conn CDT Tourer, 75 Conn SE V6, 75 Conn V6, 75 Conn CDTi Tourer, ZS 180 Join Date: Jan 2014 Location: Devon Posts: 1,986 Thanks: 1,287 Thanked 963 Times in 534 Posts	Hi Ondrej, I'm not familiar with the oil thermostat, but if the cooler isn't available, I'd check ebay or your local breakers for a good, used unit __________________

14th October 2020, 21:40	#3
clf This is my second home MG ZT CDTi Join Date: Jan 2014 Location: carrick Posts: 7,859 Thanks: 3,494 Thanked 2,657 Times in 1,973 Posts	This is a common problem, but whilst I have not heard of an oil thermostat, almost certainly the replacement thermostat you have fitted is faulty. If it is an inline thermostat you fitted, it is either faulty, fitted incorrectly, or is letting too much coolant past before it opens. The full definitive background is HERE (a very long read) How to fit the thermostat is HERE from THIS post. My personal preference is a Wahler 3029.89. If you could get a 3029.92 it would be better, but these are difficult to find, and expensive. But others are acceptable. An alternative option is the Meziere inline housing. Load on the engine and distance is important, speeds of between 40-70mph for 10 miles should see it reach temperature of 82-88 degrees. There is a lot of information about this issue and modification. Search inline thermostat and you will see. If you decide to read it all, the winter will be over, and you will not notice lol. If you really want to replace the oil cooler, Mickyboy has one listed HERE. But I would still confirm the inline thermostats first. __________________ It is not gloss primer .............. it is duct tape silver! Last edited by clf; 14th October 2020 at 22:20..

15th October 2020, 09:13	#5
Arctic Give to Learn Freelander 2 Join Date: Aug 2010 Location: West Midlands Posts: 18,699 Thanks: 1,155 Thanked 6,407 Times in 3,874 Posts	this maybe what you are after double check before purchase. http://mgrovergenuine.co.uk/genuine-...-transmission/ __________________ Arctic Givology Learn to Give Everything is Achievable ad altiora tendo. Check out our Nano meet dates http://www.midlandsnanomeets.co.uk/ http://www.the75andztclub.co.uk/index.php?thepage=howto " You do the work , we supply the expertise "

15th October 2020, 09:27	#6
ceedy This is my second home All Trophy Blue ,ZT260#50 , ZT CDTI Auto, ZR105+ and 1.8T Firefrost spoiling the Set . Join Date: Nov 2006 Location: Nr Sherborne But in Somerset.. Posts: 6,075 Thanks: 916 Thanked 1,214 Times in 768 Posts	Can't see why anything outside of the motor and Cooling circuit should have any effect on the engine temperature in a negative temps way ? . Any effect/load would only ever be temps upwards if at all ? C. __________________ The Three Bloo's Wifey's Zr105, MY CDTI & 260 #50 and Number One sons 1.8T in Firefrost When I were a lad Zero to 142 in 10.25 secs at the Pod on my Blown Norton. 210 Kart Champ in 70's

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14th October 2020, 10:12	#1
AnderN Newbie MG ZT Join Date: Sep 2009 Location: Brno Posts: 5 Thanks: 0 Thanked 1 Time in 1 Post	Diesel automatic oil cooler Greetings, I have a 2004 ZT (facelift) saloon diesel with JATCO automatic gearbox. At some point the car couldn't reach and keep the engine operating temperature so I changed the thermostat but unfortunately no change in behavior. Even after a long run the engine was still able to make only around 65°C (instead of ~90°C). I started to suspect the automatic transmission oil cooler that also includes one thermostat inside but I can't find it anywhere to buy (either the thermostat or the whole cooler). Other cars with the same engine/gearbox combination (such as LR Freelander) seem to use a different cooler for the gearbox oil. As a workaround, I have added one more thermostat to the cooling circuit, this improved the operating temperature to ~80-85°C. It is definitely better than before and far better than experiencing some overheating problems but it's still not perfect. Question -- do you know where to buy the transmission oil cooler for my car? It appears to no longer available at rimmers or anywhere else: https://rimmerbros.com/Item--i-GRID001593 Or is there anyone in here who had the same problem? How did you solve it? Thanks in advance!

22nd October 2020, 23:10	#7
AnderN Newbie MG ZT Join Date: Sep 2009 Location: Brno Posts: 5 Thanks: 0 Thanked 1 Time in 1 Post	Thank you very much for your fast answers, gentlemen! I'll try to shed more light in some parts of the story ... I have this car for 10+ years now and made over 100k miles on it. Currently it has around 200k miles on the clock (~300k km). It is an excellent car and I love it, for a long time it was the only facelifted ZT here in the Czech Republic (now there are 2-3 more as the prices fell down rapidly a couple years ago). Anyway, to your points: @Sonic ZS: no chance to get a used oil cooler anywhere around @clf: thanks for the links, it is a long reading and with the three small kids home it took me a while to read through it :-) anyway, the car is typically used for longer distances (60-120 miles but even longer) at speeds around 70-90 mph on highways ... there are only two situations when the engine can fully reach the operating temperature -- either speeds above 100 mph or a long standstill traffic during tropical days in summer. In such case the temperature can go over 100°C and I can hear the fan running (I think it starts at 106°C according to both the RAVE and my own experience) ... although I haven't tried to boil it on a home cooker I'm quite sure the new thermostat works properly ;-) the extra inline thermostat that I installed helped to improve the temperature, it is just not 100% @SD1too: no, I need the later 'fluid' cooler, #1 at this page: https://rimmerbros.com/Item--i-GRID001593 @Arctic: thanks but that's just one of the hoses, I need the cooler, see the link above @ceedy: with the latest 'fluid' cooler (see the link above) the engine coolant goes through the transmission oil cooler (the oil is cooled by the same water as the engine) ... the oil cooler is supposed to have an extra thermostat built in but if this thermostat is broken and remains open permanently, the engine starts being cooled more than needed, therefore cannot reach the operating temperature unless it is under very high load (100+ mph on a highway or something like that). I was trying to find out if the same transmission oil cooler was used in some other cars including BMWs, too. Unfortunately, I didn't find any. Even in R75/ZT there were three different transmission oil coolers -- one for petrol engines, and two for diesel (the original air cooler and the later fluid cooler that I have in my car). Obviously, the BMWs with M47R engine used different automatic transmissions and different coolers at their time.

23rd October 2020, 09:04	#9
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,547 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Yes the ATF won't have an adverse effect on the engine cooling.